All appliances can work with OpenTherm and with the thermostat I is possible to control the boiler and the ventilation system. But when I connect all together, the thermostat displays "no communication". When I connect the boiler separately it works fine oubviously, when I connect the ventilation-unit separately I get a connection but no control.

So, both appliances give out power to the thermostat and I think that's the problem. Is there any way to connect all the appliances together and have control over the boiler and the ventilation-unit?

I have searched the internet for hours with no result, so if anyone can help me please do!

Jaymin wrote:Today the Brink company contacted me, and the way I want to connect all is not possible. Their opentherm connection only works with their CO2 wireless ventilation control-unit.

Ah, I noticed the Brink Renovent Excellent HRU documentation doesn't use the OpenTherm logo and the device is not OpenTherm-compliant. I've got a Brink Renovent Excellent 300 connected with my OTGW and Chronotherm Vision Modulation room controller and noticed it doesn't support data-ID 0. The Chronotherm Vision refuses to set the Control Setpoint V/H (data-ID 71).